U.S. patent number 9,255,801 [Application Number 13/922,801] was granted by the patent office on 2016-02-09 for yaw rate sensor.
This patent grant is currently assigned to ROBERT BOSCH GMBH. The grantee listed for this patent is Thorsten Balslink, Burkhard Kuhlmann, Daniel Christoph Meisel, Rolf Scheben, Benjamin Schmidt. Invention is credited to Thorsten Balslink, Burkhard Kuhlmann, Daniel Christoph Meisel, Rolf Scheben, Benjamin Schmidt.
United States Patent |
9,255,801 |
Kuhlmann , et al. |
February 9, 2016 |
Yaw rate sensor
Abstract
A yaw rate sensor, including a substrate and a main extension
plane, for detecting a yaw rate around a first direction in
parallel to the main extension plane, a first Coriolis mass, and a
second Coriolis mass, and a drive device configured to drive the
first and second Coriolis masses in parallel to a drive direction
perpendicular to the first direction, the first and second Coriolis
masses, for a yaw rate around the first direction, experiencing a
Coriolis acceleration in parallel to a detection direction, which
is perpendicular to the drive and first directions, the first and
second Coriolis masses having first/second partial areas and
third/fourth partial areas, respectively. The first and third
partial areas are farther from the axis of symmetry in parallel to
the first direction, and the second and fourth partial areas are
closer to the axis of symmetry in parallel to the first
direction.
Inventors: |
Kuhlmann; Burkhard (Reutlingen,
DE), Scheben; Rolf (Stuttgart, DE), Meisel;
Daniel Christoph (Reutlingen, DE), Schmidt;
Benjamin (Stuttgart, DE), Balslink; Thorsten
(Kirchentellinsfurt, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Kuhlmann; Burkhard
Scheben; Rolf
Meisel; Daniel Christoph
Schmidt; Benjamin
Balslink; Thorsten |
Reutlingen
Stuttgart
Reutlingen
Stuttgart
Kirchentellinsfurt |
N/A
N/A
N/A
N/A
N/A |
DE
DE
DE
DE
DE |
|
|
Assignee: |
ROBERT BOSCH GMBH (Stuttgart,
DE)
|
Family
ID: |
49487171 |
Appl.
No.: |
13/922,801 |
Filed: |
June 20, 2013 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20130340522 A1 |
Dec 26, 2013 |
|
Foreign Application Priority Data
|
|
|
|
|
Jun 20, 2012 [DE] |
|
|
10 2012 210 374 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01C
19/56 (20130101); G01C 19/5747 (20130101) |
Current International
Class: |
G01P
3/44 (20060101); G01C 19/56 (20120101); G01C
19/5747 (20120101) |
Field of
Search: |
;73/504.12 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Williams; Hezron E
Assistant Examiner: Shabman; Mark A
Attorney, Agent or Firm: Kenyon & Kenyon LLP
Claims
What is claimed is:
1. A yaw rate sensor, comprising: a substrate, which has a main
extension plane, for detecting a yaw rate around a first direction
extending in parallel to the main extension plane; a drive device;
a first Coriolis mass; a second Coriolis mass, the drive device
being configured to drive the first Coriolis mass and the second
Coriolis mass in parallel to a drive direction, which extends
perpendicularly to the first direction, the first Coriolis mass and
the second Coriolis mass, in the case of a yaw rate around the
first direction, experiencing a Coriolis acceleration in parallel
to a detection direction, which extends perpendicularly to both the
drive direction and perpendicularly to the first direction, the yaw
rate sensor having an axis of symmetry which extends in parallel to
the first direction with respect to the Coriolis masses, wherein
the first Coriolis mass has a first partial area and a second
partial area, the second Coriolis mass has a third partial area and
a fourth partial area, the first partial area and the third partial
area being situated farther away from the axis of symmetry
extending in parallel to the first direction, and the second
partial area and the fourth partial area being situated closer to
the axis of symmetry extending in parallel to the first direction;
a first electrode, which forms a first capacitance with the first
partial area, is situated opposite to the first partial area; a
second electrode, which forms a second capacitance with the second
partial area, is situated opposite to the second partial area; a
third electrode, which forms a third capacitance with the third
partial area, is situated opposite to the third partial area; a
fourth electrode, which forms a fourth capacitance with the fourth
partial area, is situated opposite to the fourth partial; wherein
an attachment of the first Coriolis mass and the second Coriolis
mass is on the substrate or on the drive device, wherein the
configurations of the first, second, third, and fourth electrodes
are provided so that for a rotational acceleration around the first
direction, the changes, which are caused by the deflections of or
force effects on the first, second, third, and fourth partial areas
are in parallel to the detection direction, of either the first and
third capacitances and the second and fourth capacitances or the
first and second capacitances and the third and fourth capacitances
mutually compensate for one another, wherein the first partial area
and the second partial area have different masses per unit area in
parallel to the main extension plane of the first Coriolis mass,
and the third partial area and the fourth partial area have
different masses per unit area in parallel to the main extension
plane of the second Coriolis mass.
2. The yaw rate sensor of claim 1, wherein the drive device has a
first drive element and a second drive element, the first drive
element driving the first Coriolis mass in parallel to the drive
direction and the second drive element driving the second Coriolis
mass in parallel to the drive direction, the first Coriolis mass
being configured so it is tiltable around a first tilting axis in
parallel to the first direction in relation to the first drive
element, and the second Coriolis mass is tiltable around a second
tilting axis in parallel to the first direction relative to the
second drive element.
3. The yaw rate sensor of claim 1, wherein the first Coriolis mass
is connected to the first drive element with a first torsion
suspension in the area of the first tilting axis, and the second
Coriolis mass is connected to the second drive element with a
second torsion suspension in the area of the second tilting
axis.
4. The yaw rate sensor of claim 1, wherein the drive device is
configured to drive the first Coriolis mass and the second Coriolis
mass in opposite directions to one another in the drive
direction.
5. The yaw rate sensor of claim 1, wherein the drive device has a
drive frame, the drive frame having four angled elements, which are
attached in the corners of the frame so they may be rotationally
deflected on the substrate, each two of the angled elements being
connected to one another via U-shaped spring elements.
6. A yaw rate sensor, comprising: a substrate, which has a main
extension plane, for detecting a yaw rate around a first direction
extending in parallel to the main extension plane; a drive device;
a first Coriolis mass; a second Coriolis mass, the drive device
being configured to drive the first Coriolis mass and the second
Coriolis mass in parallel to a drive direction, which extends
perpendicularly to the first direction, the first Coriolis mass and
the second Coriolis mass, in the case of a yaw rate around the
first direction, experiencing a Coriolis acceleration in parallel
to a detection direction, which extends perpendicularly to both the
drive direction and perpendicularly to the first direction, the yaw
rate sensor having an axis of symmetry which extends in parallel to
the first direction with respect to the Coriolis masses, wherein
the first Coriolis mass has a first partial area and a second
partial area, the second Coriolis mass has a third partial area and
a fourth partial area, the first partial area and the third partial
area being situated farther away from the axis of symmetry
extending in parallel to the first direction, and the second
partial area and the fourth partial area being situated closer to
the axis of symmetry extending in parallel to the first direction;
a first electrode, which forms a first capacitance with the first
partial area, is situated opposite to the first partial area; a
second electrode, which forms a second capacitance with the second
partial area, is situated opposite to the second partial area; a
third electrode, which forms a third capacitance with the third
partial area, is situated opposite to the third partial area; a
fourth electrode, which forms a fourth capacitance with the fourth
partial area, is situated opposite to the fourth partial; wherein
an attachment of the first Coriolis mass and the second Coriolis
mass is on the substrate or on the drive device, wherein the
configurations of the first, second, third, and fourth electrodes
are provided so that for a rotational acceleration around the first
direction, the changes, which are caused by the deflections of or
force effects on the first, second, third, and fourth partial areas
are in parallel to the detection direction, of either the first and
third capacitances and the second and fourth capacitances or the
first and second capacitances and the third and fourth capacitances
mutually compensate for one another, wherein the mass per unit area
in parallel to the main extension plane of the first Coriolis mass
decreases with increasing distance from the axis of symmetry of the
yaw rate sensor extending in parallel to the first direction, and
the mass per unit area in parallel to the main extension plane of
the second Coriolis mass decreases with increasing distance from
the axis of symmetry of the yaw rate sensor extending in parallel
to the first direction.
7. A yaw rate sensor, comprising: a substrate, which has a main
extension plane, for detecting a yaw rate around a first direction
extending in parallel to the main extension plane; a drive device;
a first Coriolis mass; a second Coriolis mass, the drive device
being configured to drive the first Coriolis mass and the second
Coriolis mass in parallel to a drive direction, which extends
perpendicularly to the first direction, the first Coriolis mass and
the second Coriolis mass, in the case of a yaw rate around the
first direction, experiencing a Coriolis acceleration in parallel
to a detection direction, which extends perpendicularly to both the
drive direction and perpendicularly to the first direction, the yaw
rate sensor having an axis of symmetry which extends in parallel to
the first direction with respect to the Coriolis masses, wherein
the first Coriolis mass has a first partial area and a second
partial area, the second Coriolis mass has a third partial area and
a fourth partial area, the first partial area and the third partial
area being situated farther away from the axis of symmetry
extending in parallel to the first direction, and the second
partial area and the fourth partial area being situated closer to
the axis of symmetry extending in parallel to the first direction;
a first electrode, which forms a first capacitance with the first
partial area, is situated opposite to the first partial area; a
second electrode, which forms a second capacitance with the second
partial area, is situated opposite to the second partial area; a
third electrode, which forms a third capacitance with the third
partial area, is situated opposite to the third partial area; a
fourth electrode, which forms a fourth capacitance with the fourth
partial area, is situated opposite to the fourth partial; wherein
an attachment of the first Coriolis mass and the second Coriolis
mass is on the substrate or on the drive device, wherein the
configurations of the first, second, third, and fourth electrodes
are provided so that for a rotational acceleration around the first
direction, the changes, which are caused by the deflections of or
force effects on the first, second, third, and fourth partial areas
are in parallel to the detection direction, of either the first and
third capacitances and the second and fourth capacitances or the
first and second capacitances and the third and fourth capacitances
mutually compensate for one another, wherein, for a rotational
acceleration around the first direction, the force action, in
parallel to the detection direction, on the first partial area and
the third partial area is greater than the force action, in
parallel to the detection direction, on the second partial area and
on the fourth partial area, and the area in parallel to the main
extension plane of the first electrode and the third electrode is
smaller than the area in parallel to the main extension plane of
the second electrode and the fourth electrode.
8. A yaw rate sensor, comprising: a substrate, which has a main
extension plane, for detecting a yaw rate around a first direction
extending in parallel to the main extension plane; a drive device;
a first Coriolis mass; a second Coriolis mass, the drive device
being configured to drive the first Coriolis mass and the second
Coriolis mass in parallel to a drive direction, which extends
perpendicularly to the first direction, the first Coriolis mass and
the second Coriolis mass, in the case of a yaw rate around the
first direction, experiencing a Coriolis acceleration in parallel
to a detection direction, which extends perpendicularly to both the
drive direction and perpendicularly to the first direction, the yaw
rate sensor having an axis of symmetry which extends in parallel to
the first direction with respect to the Coriolis masses, wherein
the first Coriolis mass has a first partial area and a second
partial area, the second Coriolis mass has a third partial area and
a fourth partial area, the first partial area and the third partial
area being situated farther away from the axis of symmetry
extending in parallel to the first direction, and the second
partial area and the fourth partial area being situated closer to
the axis of symmetry extending in parallel to the first direction;
a first electrode, which forms a first capacitance with the first
partial area, is situated opposite to the first partial area; a
second electrode, which forms a second capacitance with the second
partial area, is situated opposite to the second partial area; a
third electrode, which forms a third capacitance with the third
partial area, is situated opposite to the third partial area; a
fourth electrode, which forms a fourth capacitance with the fourth
partial area, is situated opposite to the fourth partial; wherein
an attachment of the first Coriolis mass and the second Coriolis
mass is on the substrate or on the drive device, wherein the
configurations of the first, second, third, and fourth electrodes
are provided so that for a rotational acceleration around the first
direction, the changes, which are caused by the deflections of or
force effects on the first, second, third, and fourth partial areas
are in parallel to the detection direction, of either the first and
third capacitances and the second and fourth capacitances or the
first and second capacitances and the third and fourth capacitances
mutually compensate for one another, wherein, for a rotational
acceleration around the first direction, the force action, in
parallel to the detection direction, on the first partial area, the
second partial area, the third partial area, and the fourth partial
area is of equal size, and the area in parallel to the main
extension plane of the first electrode, the second electrode, the
third electrode, and the fourth electrode is of equal size.
Description
RELATED APPLICATION INFORMATION
The present application claims priority to and the benefit of
German patent application no. 10 2012 210 374.0, which was filed in
Germany on Jun. 20, 2012, the disclosure of which is incorporated
herein by reference.
FIELD OF THE INVENTION
The present invention is directed to a yaw rate sensor.
BACKGROUND INFORMATION
Yaw rate sensors are known from the related art. For example, a yaw
rate sensor having two oscillating mass elements is discussed in
publication WO 03064975 A1. Micromechanical yaw rate sensors for
measuring yaw rates around a direction in parallel to the main
extension plane of the substrate of the sensor are typically
configured with planar oscillating masses or as masses rotating in
the plane, which experience a Coriolis force in a detection
direction, i.e., perpendicularly to the main extension plane, upon
the occurrence of a rotational movement around the direction in
parallel to the main extension plane. This Coriolis force is either
ascertained via the electrostatic counterforce required for the
location feedback (closed-loop regulation) or, for example,
measured via the capacitance change due to the distance change to
the substrate (open-loop operation).
Such yaw rate sensors may have two oscillating masses (partial
oscillators), which are driven into an anti-parallel mode. If a yaw
rate is present, an anti-parallel detection oscillation is
initiated by the Coriolis force, which is capacitively detected and
converted into a yaw rate with the aid of analysis electronics. It
is related art that a partial oscillator is constructed from a
drive oscillator and a Coriolis oscillator. The drive oscillator
only participates in the drive movement and not in the detection
oscillation. The Coriolis element participates in both the drive
oscillation and the detection oscillation.
In addition to the Coriolis force, there are further forces for
practically relevant usage cases, to which sensors or parts thereof
are subjected and which may also induce a signal or which could
corrupt the signal assigned to the Coriolis force, in particular
inertial forces induced by linear accelerations and by rotational
accelerations. The occurrence of these forces disadvantageously
results in false signals during operation, because, for example, a
rotational acceleration, for example, in the form of a rotational
oscillation around the sensitive axis, directly results in a yaw
rate signal. In particular if the rotational oscillation occurs at
the frequency at which the yaw rate sensor is driven and occurs in
phase with a Coriolis force, a particularly large possibility for
interference results.
SUMMARY OF THE INVENTION
It is therefore an object of the exemplary embodiments and/or
exemplary methods of the present invention to provide a yaw rate
sensor and a method for operating a yaw rate sensor which do not
have the disadvantages of the related art and which are insensitive
to both linear accelerations in parallel to the detection direction
and to rotational accelerations according to the sensitive
direction of the yaw rate sensor.
According to the present system, a yaw rate sensor is provided
including a substrate, which has a main extension plane, for
detecting a yaw rate around a first direction extending in parallel
to the main extension plane, the yaw rate sensor having a drive
device, a first Coriolis mass, and a second Coriolis mass, the
drive device being configured to drive the first Coriolis mass and
the second Coriolis mass in parallel to a drive direction extending
perpendicularly to the first direction, the first Coriolis mass and
the second Coriolis mass, for a yaw rate around the first
direction, experiencing a Coriolis acceleration in parallel to a
detection direction, which is both perpendicular to the drive
direction and perpendicular to the first direction, the first
Coriolis mass having a first partial area and a second partial
area, the second Coriolis mass having a third partial area and a
fourth partial area, the first and third partial areas being
situated farther away from the axis of symmetry extending in
parallel to the first direction, and the second and fourth partial
areas being situated closer to the axis of symmetry extending in
parallel to the first direction, a first electrode, which forms a
first capacitance with the first partial area, being situated
opposite to the first partial area, a second electrode, which forms
a second capacitance with the second partial area, being situated
opposite to the second partial area, a third electrode, which forms
a third capacitance with the third partial area, being situated
opposite to the third partial area, a fourth electrode, which forms
a fourth capacitance with the fourth partial area, being situated
opposite to the fourth partial area, the attachment of the first
and second Coriolis masses on the substrate or on the drive device
and the arrangement and configuration of the first, second, third,
and fourth electrodes being provided in such a way that, in case of
a rotational acceleration around the first direction, the changes,
which are caused by deflections of the first, second, third, and
fourth partial areas in parallel to the detection direction, of
either the first and third capacitances and the second and fourth
capacitances or the first and second capacitances and the third and
fourth capacitances, mutually compensate for one another.
In particular, the yaw rate sensor according to the present
invention as described herein has the advantage over the related
art that it is less sensitive in relation to interfering
accelerations in the form of rotational accelerations with respect
to rotations around a direction which corresponds to the first
direction (i.e., the direction which corresponds to the sensitive
or measuring direction of the yaw rate sensor), and in the form of
linear accelerations in parallel to the detection direction of the
yaw rate sensor, or that the effect of such interfering
accelerations may be differentiated from the effect of the actual
yaw rate to be detected around the particular direction. According
to the exemplary embodiments and/or exemplary methods of the
present invention, the Coriolis masses are configured or attached
(on the substrate or on the drive device) and the first, second,
third, and fourth electrodes are configured in such a way that in
the event of a rotational acceleration around the sensitive
direction, i.e., around the first direction, the changes caused by
deflections of or the force action on the first, second, third, and
fourth partial areas of the Coriolis masses in a direction in
parallel to the detection direction either of the first and third
capacitances and the second and fourth capacitances or of the first
and second capacitances and the third and fourth capacitances
mutually compensate for one another.
In this way, advantageously, due to the mechanical configuration of
the yaw rate sensor (in the form of the suspension or the
attachment of the Coriolis mass on the substrate or on the drive
device and in the form of the configuration of the first, second,
third, and fourth electrodes) and by the electrical interconnection
of the yaw rate sensor (in the form of the resulting measuring
signal of the capacitance changes of the first, second, third, and
fourth capacitances in the event of deflection of or force action
on the first, second, third, and fourth partial areas), rotational
accelerations have no influence at all on the measuring signal to
be analyzed or are only incorporated in extremely suppressed form
in this measuring signal.
According to the exemplary embodiments and/or exemplary methods of
the present invention, the yaw rate sensor is configured in such a
way that a yaw rate around a first direction extending in parallel
to the main extension plane of the substrate is detected (i.e., the
case of an .OMEGA..sub.x sensor or an .OMEGA..sub.y sensor,
therefore a yaw rate sensor whose sensitive direction is a rotation
around a first direction extending in parallel to the main
extension plane). In this case, the drive device is provided in
such a way that the first Coriolis mass and the second Coriolis
mass are driven in parallel to the drive direction extending
perpendicularly to the first direction, the drive direction also
extending in parallel to the main extension plane. The detection
direction extends perpendicularly to the main extension plane.
Embodiments and refinements of the present invention may be derived
from the subclaims, and also the description with reference to the
drawings.
According to one of the exemplary embodiments and/or exemplary
methods of the present invention, it is provided that the drive
device has a first drive element and a second drive element, the
first drive element driving the first Coriolis mass in parallel to
the drive direction, and the second drive element driving the
second Coriolis mass in parallel to the drive direction, the first
Coriolis mass being configured to be tiltable relative to the first
drive element around a first tilting axis in parallel to the first
direction, and the second Coriolis mass being tiltable relative to
the second drive element around a second tilting axis in parallel
to the first direction. It is thus advantageously possible to
compensate particularly well for the effect of an interfering
rotational acceleration, in particular a rotational acceleration
having frequency components in the frequency range of the drive
oscillation, and therefore to differentiate it from a corresponding
yaw rate.
According to another of the exemplary embodiments and/or exemplary
methods of the present invention, it is provided that the first
partial area and the second partial area have different masses per
unit area in parallel to the main extension plane of the first
Coriolis mass, and the third partial area and the fourth partial
area have different masses per unit area in parallel to the main
extension plane of the second Coriolis mass, or the mass per unit
area of the first Coriolis mass in parallel to the main extension
plane decreases with increasing distance from the axis of symmetry
of the yaw rate sensor extending in parallel to the first direction
(in particular in inverse proportion to the square of the distance
to the axis of symmetry), and the mass per unit area of the second
Coriolis mass in parallel to the main extension plane decreases
with increasing distance from the axis of symmetry of the yaw rate
sensor extending in parallel to the first direction. It is thus
advantageously provided according to the exemplary embodiments
and/or exemplary methods of the present invention to cause
different movement behavior or a different deflection or at least
(in particular in closed-loop systems) a different force action on
the first and third partial areas or on the second and fourth
partial areas of the first and second Coriolis masses for the case
of a rotational acceleration, on the one hand, and a yaw rate, on
the other hand, so that in cooperation with the embodiment of the
electrode system of the first, second, third, and fourth
electrodes, suppression or compensation (in the measuring signal)
of the effect of a rotational acceleration results.
According to another of the exemplary embodiments and/or exemplary
methods of the present invention, it is provided that in the case
of a rotational acceleration around the first direction, the
deflection or force action--in parallel to the detection
direction--of the first partial area and the third partial area is
greater than the deflection or force action--in parallel to the
detection direction--of the second partial area and the fourth
partial area, and the area in parallel to the main extension plane
of the first electrode and the third electrode is smaller than the
area in parallel to the main extension plane of the second
electrode and the fourth electrode, or in the case of a rotational
acceleration around the first direction, the deflection or force
action--in parallel to the detection direction--of the first
partial area, the second partial area, the third partial area, and
the fourth partial area is equal in amount, and the area in
parallel to the main extension plane of the first electrode, the
second electrode, the third electrode, and the fourth electrode is
equal in size.
It is thus advantageously possible according to the present
invention to compensate for the effect of a rotational acceleration
in the measuring signal.
According to another refinement of the exemplary embodiments and/or
exemplary methods of the present invention, it is provided that the
first Coriolis mass is connected to the first drive element with
the aid of a first torsion suspension in the area of the first
tilting axis, and the second Coriolis mass is connected to the
second drive element with the aid of a second torsion suspension in
the area of the second tilting axis. It is thus advantageously
possible according to the exemplary embodiments and/or exemplary
methods of the present invention that a particularly simple and
nonetheless robust mechanical structure of the yaw rate sensor is
implementable.
According to another embodiment, it is provided that the drive
device is configured to drive the first Coriolis mass and the
second Coriolis mass each in opposite directions to one another in
the drive direction or that the drive device has a drive frame, the
drive frame having four angled elements, which are attached in the
corners of the frame so they may be rotationally deflected on the
substrate, two of the angled elements each being connected to one
another via a U-shaped spring element.
Exemplary embodiments of the present invention are shown in the
drawings and explained in greater detail in the following
description.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 shows a schematic diagram of a conventional yaw rate sensor
as an .OMEGA..sub.y sensor according to the related art.
FIG. 2 shows various embodiment variants of yaw rate sensors
according to the present invention.
FIG. 3 shows various embodiment variants of yaw rate sensors
according to the present invention.
FIG. 4 shows various embodiment variants of yaw rate sensors
according to the present invention.
FIG. 5 shows various embodiment variants of yaw rate sensors
according to the present invention.
DETAILED DESCRIPTION
Identical parts are always provided with identical reference
numerals in the various figures and are therefore also generally
only cited or mentioned once in each case.
FIG. 1 shows a schematic diagram of a conventional yaw rate sensor
100, which is micromechanically manufactured in particular, and
which is provided for detecting yaw rates around a first direction
OR (in the example of FIGS. 1 and 2 of an .OMEGA..sub.y sensor,
this corresponds to the y axis), and which is implemented on a
substrate 101, which has a main extension plane 110 and which also
specifies this plane for the sensor or yaw rate sensor. Such yaw
rate sensors include two oscillating masses (partial oscillators),
which are driven into an antiparallel mode along a drive direction
AR (in the example of FIG. 1, this corresponds to the x axis),
which is perpendicular to first direction OR. If a yaw rate exists,
an antiparallel detection oscillation (in parallel to a detection
direction DR, which is both perpendicular to first direction OR and
perpendicular to drive direction AR) is initiated by the Coriolis
force, which is capacitively detected and converted into a yaw rate
with the aid of analysis electronics.
Substrate 101 and main extension plane 110 are only shown in FIG.
1, but are similarly present in all FIGS. 1 through 5, since all of
these figures show top views of the sensor structures, i.e., the
plane of the drawing corresponds to main extension plane 110. Such
a partial oscillator of a yaw rate sensor conventionally includes a
drive oscillator as drive device 1 and a Coriolis oscillator as a
first Coriolis mass 5. The other partial oscillator includes a
second Coriolis mass 5'. Drive device 1 includes a first drive
element 12 and a second drive element 12' and drives first Coriolis
mass 5 with the aid of first drive element 12 and drives second
Coriolis mass 5' in parallel (and according to the anti-parallel
oscillating mode) to drive direction AR with the aid of the second
drive element.
In the yaw rate sensor according to FIG. 1, the drive oscillator is
anchored with the aid of springs 2 via anchor points 3 on substrate
101. Springs 2 are U-shaped and are soft along the x direction (in
the example corresponding to drive direction AR). Along the y
direction (in the example, corresponding to first direction OR),
they are stiff. They are also stiff along the z direction (in the
example corresponding to detection direction DR), in that the layer
thickness is configured to be greater than the bar width. Drive
device 1 is in particular electrostatically driven in resonance
with its natural frequency with the aid of interdigital structures
(not shown). Arrows 4 point in the direction of the drive movement,
the partial oscillators, i.e., first and second Coriolis masses 5,
5', oscillating in counter phase in relation to one another, i.e.,
one partial oscillator moves--at least partially--in the negative x
direction when the other partial oscillator moves--at least
partially--in the positive x direction and vice versa.
First and second Coriolis masses 5, 5' are connected to drive
device 1 via coupling springs 6, so that first and second Coriolis
masses 5, 5' may execute both drive movement 4 and detection
movement 8. The detection movement along the z axis occurs due to a
Coriolis acceleration or Coriolis force, which results from yaw
rate .OMEGA..sub.y around the y axis and velocity v.sub.x along the
x axis according to F.sub.Coriolis=2*m*v.sub.x.times..OMEGA..sub.y
(vectorial cross product). Both the drive movement and the
detection movement of the two partial oscillators are coupled with
the aid of a coupling structure 7 between first and second Coriolis
masses 5, 5'. The detection electrodes (not shown) are located, for
example, below first and second Coriolis masses 5, 5' on substrate
101.
Conventional yaw rate sensors may have an acceleration sensitivity
and a rotational acceleration sensitivity depending on the
configuration. This means that a rotational acceleration, for
example, in the form of a rotational oscillation around the
sensitive axis (first direction OR, in the example the y axis),
directly results in a yaw rate signal. In particular if the
rotational oscillations occur at frequency f.sub.A (at which the
yaw rate sensor is driven) and in phase with a Coriolis force, a
particularly high susceptibility to interference results. A
rotational acceleration around first direction OR (the y axis here)
also results in an equivalent force, which typically may not be
differentiated from a Coriolis force. Furthermore, a linear
acceleration along detection direction DR (the z axis here) results
in an unintentional deflection of first and second Coriolis masses
5, 5' or force action on first and second Coriolis masses 5, 5'
along detection direction DR (in the example, the z axis).
According to FIGS. 2 through 5, a first (FIG. 2), a second (FIG.
3), a third (FIG. 4), and a fourth (FIG. 5) embodiment variant of a
yaw rate sensor 100 according to the present invention are
schematically shown in a top view of yaw rate sensor 100, i.e., the
plane of the drawing corresponds to main extension plane 110.
According to the exemplary embodiments and/or exemplary methods of
the present invention, it is provided in all embodiment variants
that first Coriolis mass 5 has a first partial area 9 and a second
partial area 10, and second Coriolis mass 5' has a third partial
area 9' and a fourth partial area 10'. In relation to an axis of
symmetry of yaw rate sensor 100, which extends in parallel to first
direction OR with respect to Coriolis masses 5, 5', first and third
partial areas 9, 9' are situated farther away from the axis of
symmetry extending in parallel to first direction OR than second
and fourth partial areas 10, 10'.
A first electrode E9 (which is fixed in relation to the anchor
points or the substrate in particular, which may be fixedly
connected to the substrate) forms a first capacitance with first
partial area 9 and is situated opposite to first partial area 9
(for example, above, below, or above and below and/or adjacent to
the partial area). A second electrode E10 (which is fixed in
relation to the anchor points or the substrate, which may be
fixedly connected to the substrate) forms a second capacitance with
second partial area 10 and is situated opposite to second partial
area 10. A third electrode E9' (which is fixed in relation to the
anchor point for the substrate in particular, which may be fixedly
connected to the substrate) forms a third capacitance with third
partial area 9' and is situated opposite to third partial area 9'.
A fourth electrode E10' (which is fixed in relation to the anchor
points or the substrate in particular, which may be fixedly
connected to the substrate) forms a fourth capacitance with fourth
partial area 10' and is situated opposite to fourth partial area
10'.
These electrodes are interconnected in particular to form total
capacitances CP and CN and may form difference CP-CN. A yaw rate
around first direction OR (this corresponds to the x direction in
all embodiment variants) causes, due to the embodiment according to
the present invention of first and second Coriolis masses 5, 5' (in
particular due to the different attachments of Coriolis masses 5,
5' on substrate 101 or on first and second drive elements 12, 12')
in all embodiment variants of the present invention, a different
configuration of the force action due to the Coriolis force on
first, second, third, and fourth partial areas 9, 10, 9', 10' of
Coriolis masses 5, 5' in relation to the configuration of the force
action of the rotational acceleration force on first, second,
third, and fourth partial areas 9, 10, 9', 10' of Coriolis masses
5, 5' in the case of a rotational acceleration around first
direction OR. This is shown in each case in the left part of FIGS.
2 through 5 on the basis of schematic arrow illustrations
perpendicular to the plane of the drawing (together with the force
action due to the linear acceleration in the detection direction (z
direction) a.sub.z on first, second, third, and fourth partial
areas 9, 10, 9', 10' of Coriolis masses 5, 5').
In this case, a larger circle having a spot in the middle
symbolizes a greater force action or a greater deflection in
parallel to the z direction (i.e., out of the plane of the drawing
toward the observer), while a smaller circle having a spot in the
middle symbolizes a lesser force action or a lesser deflection in
parallel to the z direction (i.e., out of the plane of the drawing
toward the observer). Furthermore, a larger circle having an X
symbolizes a greater force action or a greater deflection
antiparallel to the z direction (i.e., away from the observer into
the plane of the drawing), while a smaller circle having an X
symbolizes a lesser force action or a lesser deflection
antiparallel to the z direction (i.e., away from the observer into
the plane of the drawing).
The force actions on partial areas are listed hereafter. A force
action is designated as equal if it is within the scope of a
deviation of 10%, 20%, or 50%.
In the first embodiment variant (FIG. 2), in the case of a yaw rate
.OMEGA..sub.x around the x direction (i.e., around first direction
OR), the following configuration of the force action exists on
first, second, third, and fourth partial areas 9, 10, 9', 10': for
first, second, third, and fourth partial areas 9, 10, 9', 10', the
following configuration of the force action exists: The force
action on the first partial area is identical with respect to the
absolute value and with respect to the direction of the force
action on the second partial area, and the force action on the
third partial area is identical with respect to the absolute value
and with respect to the direction of the force action on the fourth
partial area.
The force action on the first partial area is identical with
respect to the absolute value and is opposite with respect to the
direction of the force action on the third partial area. The force
action is oriented along the z direction (i.e., along detection
direction DR). In the case of a rotational acceleration
d.OMEGA..sub.x/dt around the x direction (i.e., around first
direction OR), the following configuration of the force action
exists on first, second, third, and fourth partial areas 9, 10, 9',
10': The force action on the first partial area is identical with
respect to the absolute value and is opposite with respect to the
direction of the force action on the third partial area.
The force action on the second partial area is identical with
respect to the absolute value and is opposite with respect to the
direction of the force action on the fourth partial area. The force
action on the first partial area is greater with respect to the
absolute value and is identical with respect to the direction of
the force action on the second partial area. The force action is
oriented along the z direction (i.e., along detection direction
DR). In the case of a linear acceleration in parallel to detection
direction DR (z direction), the following configuration of the
force action exists on first, second, third, and fourth partial
areas 9, 10, 9', 10': The force action on the first, second, third,
and fourth partial areas is identical in absolute value and
direction. The force action is oriented along the z direction
(i.e., along detection direction DR).
In the second, third, and fourth embodiment variants (FIGS. 3
through 5), therefore, in the case of a yaw rate .OMEGA..sub.x
around the x direction (i.e., around first direction OR), the
following configuration of the force action exists on first,
second, third, and fourth partial areas 9, 10, 9', 10':
The force action on the first partial area is less with respect to
the absolute value and is identical with respect to the direction
of the force action on the second partial area and the force action
on the third partial area is less with respect to the absolute
value and is identical with respect to the direction of the force
action on the fourth partial area. The force action on the first
partial area is identical with respect to the absolute value and is
opposite with respect to the direction of the force action on the
third partial area. The force action on the second partial area is
identical with respect to the absolute value and is opposite with
respect to the direction of the force action on the fourth partial
area.
The force action is oriented along the z direction (i.e., along
detection direction DR). In the case of a rotational acceleration
d.OMEGA..sub.x/dt around the x direction (i.e., around first
direction OR), the following configuration of the force action
exists on first, second, third, and fourth partial areas 9, 10, 9',
10': The force action on the first partial area is identical with
respect to the absolute value and with respect to the direction of
the force action on the second partial area and the force action on
the third partial area is identical with respect to the absolute
value and with respect to the direction of the force action on the
fourth partial area. The force action on the first partial area is
identical with respect to the absolute value and is opposite with
respect to the direction of the force action on the third partial
area. The force action is oriented along the z direction (i.e.,
along detection direction DR).
In the case of a linear acceleration in parallel to detection
direction DR (z direction), the following configuration of the
force action exists on first, second, third, and fourth partial
areas 9, 10, 9', 10': The force action on the first partial area is
less with respect to the absolute value and is identical with
respect to the direction of the force action on the second partial
area and the force action on the third partial area is less with
respect to the absolute value and is identical with respect to the
direction of the force action on the fourth partial area. The force
action on the first partial area is identical with respect to the
absolute value and with respect to the direction of the force
action on the third partial area. The force action on the second
partial area is identical with respect to the absolute value and
with respect to the direction of the force action on the fourth
partial area. The force action is oriented along the z direction
(i.e., along detection direction DR).
It is provided according to the exemplary embodiments and/or
exemplary methods of the present invention that, on the one hand,
the attachment of first and second Coriolis masses 5, 5' on
substrate 101 or on drive device 1 and, on the other hand, the
arrangement and configuration of first, second, third, and fourth
electrodes E9, E10, E9', E10' are provided in such a way that in
the case of a rotational acceleration around first direction OR,
the changes, which are caused by deflections of or force actions on
first, second, third, and fourth partial areas 9, 10, 9', 10' in
parallel to detection direction DR, of either first and third
capacitances and second and fourth capacitances or first and second
capacitances and third and fourth capacitances mutually compensate
for one another. In this way, it is advantageously ensured
according to the present invention that a rotational acceleration
around sensitive first direction OR (in particular a rotational
acceleration in the frequency range of the excitation or drive
frequency) provides no contribution or only a small (or mutually
compensated) contribution to the measuring signal of the yaw rate
sensor.
In the first embodiment variant according to FIG. 2, it is provided
that in the case of a rotational acceleration around the x
direction, first and second partial areas 9, 10 (and third and
fourth partial areas 9', 10') are accelerated with different
strengths in parallel to the z direction. Accordingly, a
compensation of the particular partial measuring signals of
particular associated electrodes E9, E10, E9', E10' may take place
in that first and second electrodes E9, E10 and third and fourth
electrodes E9' and E10' are configured to be unequal, in particular
of unequal size (with respect to their area extension in parallel
to main extension plane 110).
It is provided in each case in the second, third, and fourth
embodiment variants according to FIGS. 3, 4, and 5 that in the case
of a rotational acceleration around the x direction, first, second,
third, and fourth partial areas 9, 10, 9', 10' are accelerated with
equal strength in parallel to the z direction. Correspondingly, a
compensation of the particular partial measuring signals of
particular associated electrodes E9, E10, E9', E10' may take place
in that first, second, third, and fourth electrodes E9, E10, E9',
E10' are configured to be identical, in particular of identical
size (with respect to their area extension in parallel to main
extension plane 110).
According to FIG. 2, Coriolis masses 5, 5' are each attached
symmetrically on substrate 101 (with the aid of spring devices 20,
which are soft in the drive direction and in the detection
direction). A first tilting axis 11 therefore extends symmetrically
(in parallel to the x direction) with respect to first Coriolis
mass 5. A second tilting axis 11' also extends symmetrically (in
parallel to the x direction) with respect to second Coriolis mass
5'. In the case of a yaw rate (around the x direction), an
equivalent force action therefore occurs on first and second
partial areas 9, 10 (or third and fourth partial areas 9', 10',
respectively) of Coriolis masses 5, 5', while in the case of a
rotational acceleration, due to the greater distance of first and
third partial areas 9, 9' from the axis of symmetry of yaw rate
sensor 100 extending in parallel to the x direction between
Coriolis masses 5, 5', a greater force action results, which may be
compensated for intrinsically with the aid of electrodes of
different sizes according to the present invention in the analysis
of the particular partial measuring signals of the electrodes.
According to FIG. 3, Coriolis masses 5, 5' are each also attached
symmetrically on substrate 101 (with the aid of spring devices 20
which are soft in the drive direction and in the detection
direction). However, in the case of the second embodiment variant,
it is provided that there is a different mass distribution per unit
area of Coriolis masses 5, 5' in parallel to main extension plane
110, and specifically with a greater mass in second and fourth
partial areas 10, 10' in relation to first and third partial areas
9, 9' or with a mass distribution of Coriolis masses 5, 5' in such
a way that the mass per unit area decreases with increasing
distance to the axis of symmetry (between Coriolis masses 5, 5') of
yaw rate sensor 100, which extends in parallel to the x direction.
Accordingly, first and second tilting axes 11, 11' do not extend
symmetrically (in parallel to the x direction) in relation to first
Coriolis mass 5 or in relation to second Coriolis mass 5',
respectively.
In the case of a yaw rate (around the x direction), a force action
of different size therefore results on first and second partial
areas 9, 10 (or third and fourth partial areas 9', 10',
respectively) of Coriolis masses 5, 5', while in the event of a
rotational acceleration, due to the greater distance of first and
third partial areas 9, 9' from axis of symmetry of yaw rate sensor
100, which extends in parallel to the x direction between Coriolis
masses 5, 5', but which is compensated for by the lower mass in
first and third partial areas 9, 9', a force action of
approximately equal size results on first, second, third, and
fourth partial areas 9, 10, 9', 10', which may be intrinsically
compensated for according to the present invention with the aid of
electrodes E9, E10, E9', E10' of equal size in the analysis of the
particular partial measuring signals of the electrodes.
However, according to FIG. 5, Coriolis masses 5, 5' are each
attached asymmetrically on substrate 101. For this purpose, spring
devices 20 which are soft in the drive direction and in the
detection direction are provided. Moreover, further tilting spring
devices 21 are provided, which are not soft in the z direction and
therefore cause tilting of first and second Coriolis masses 5, 5'
around first and second tilting axes 11, 11'. Accordingly, first
and second tilting axes 11, 11' do not extend symmetrically (in
parallel to the x direction) in relation to first Coriolis mass 5
or in relation to second Coriolis mass 5', respectively.
In the case of a yaw rate (around the x direction), a force action
of different size therefore results on first and second partial
areas 9, 10 (or third and fourth partial areas 9', 10',
respectively) of Coriolis masses 5, 5', while in the event of a
rotational acceleration, due to the greater distance of first and
third partial areas 9, 9' from the axis of symmetry of yaw rate
sensor 100, which extends in parallel to the x direction between
Coriolis masses 5, 5', but which is compensated for by the smaller
distance to respective tilting axis 11, 11' in first and third
partial areas 9, 9', a force action of approximately equal amount
results on first, second, third, and fourth partial areas 9, 10,
9', 10', which may be intrinsically compensated for according to
the present invention in the analysis of the particular partial
measuring signals of the electrodes with the aid of electrodes E9,
E10, E9', E10' of identical size.
According to FIG. 4, first Coriolis mass 5 is asymmetrically
attached on first drive element 12 with the aid of a first torsion
suspension 13 and second Coriolis mass 5' is asymmetrically
attached on second drive element 12' with the aid of a second
torsion suspension 13'. First and second torsion suspensions 13,
13' are configured to be hard or comparatively hard in drive
direction AR (y direction) and in detection direction DR for this
purpose, but permit a torsion around first and second tilting axes
11, 11', which extend in parallel to first and second torsion
suspension 13, 13'. This is possible, for example, with a
configuration of first and second torsion suspension 13, 13', which
is wider in the y direction than in the z direction. Accordingly,
first and second tilting axes 11, 11' do not extend symmetrically
(in parallel to the x direction) in relation to first Coriolis mass
5 or in relation to second Coriolis mass 5', respectively.
In the case of a yaw rate (around the x direction), a force action
of different sizes therefore results on first and second partial
areas 9, 10 (or third and fourth partial areas 9', 10',
respectively) of Coriolis masses 5, 5', while in the event of a
rotational acceleration, due to the greater distance of first and
third partial areas 9, 9' from the axis of symmetry of yaw rate
sensor 100, which extends in parallel to the x direction between
Coriolis masses 5, 5', but which is compensated for by the lesser
distance to respective tilting axis 11, 11' (or to respective
torsion suspension 13, 13') in first and third partial area 9, 9',
a force action of approximately equal amount results on first,
second, third, and fourth partial areas 9, 10, 9', 10', which may
be intrinsically compensated for in the analysis of the particular
partial measuring signals of the electrodes with the aid of
electrodes E9, E10, E9', E10' of identical size according to the
exemplary embodiments and/or exemplary methods of the present
invention.
* * * * *